BIO310H5 Lecture 2: Lecture 2 Notes
Document Summary
Electrical activity of cell membranes leads to cell-cell signaling. They all have the same structure of lipid and protein molecules kept together by non- covalent interactions. The lipid molecule are arranged in a continuous double layer, called the lipid bilayer, which is relatively impermeable to passage of most water-soluble molecules. The relative proportion of lipids and proteins present in a membrane depends on the kind of cell or organelle the membrane encloses: i. e. myelin sheath surrounding axons has little membrane proteins. Integral proteins: serve as passive transport pores and channels, active-transport pumps and carriers, membrane-linked enzymes & chemical signal receptors. Peripheral proteins: membrane-linked proteins that do not extend through membrane can act as enzymes, receptors, etc. Glycoproteins: have oligosaccharide side chains vital for cell recognition and communication. The three primary types of lipids in the cell membrane are: phosphoglycerides: have glycerol backbone, sphinogolipids: backbones made of sphingosine bases, sterols: like cholesterol, are nonpolar and only slightly soluble in water.
